Getting real time data in Tkinter

Question

Consider the code below:

from tkinter import *

screen = Tk()

e =Entry()
e.pack()


screen.mainloop()

Now how to get to display the length of the characters entered in the e entry widget in real-time? It doesn't matter if the data is displayed in the GUI or Corresponding terminal

What's the purpose of getting the data? Are you wanting to do validation (eg: limit input to numbers only)? — Bryan Oakley, Apr 04 '21 at 04:40

score 2 · Accepted Answer · answered Apr 04 '21 at 04:22

There are atleast 3 ways to do this here with one being better than the other:

Using trace from StringVar:

def func(*args):
    print(len(var.get()))

var = StringVar()

e = Entry(screen,textvariable=var)
e.pack()

var.trace('w',func)

Every time the value of var is changed, func will be called.

Using bind to each key release:

def func(*args):
    print(len(e.get()))

e.bind('<KeyRelease>',func)

Using after(ms,func) to keep repeating the function:

def func():
    print(len(e.get()))
    screen.after(500,func)

func()

As you can see, the first method is more efficient as it does not unnecessarily prints out values when you select all the items(with Ctrl+A) and so on. Using after() will be the most ridiculous method as it will keep printing the length always as there are no restrictions provided.

Getting real time data in Tkinter

1 Answers1